Although you may certainly be able to find one to purchase (e-bay or wherever) you cannot buy one from Verizon. Verizon, at this point, requires customers to pay the monthly fee. This monthly fee includes support and replacement if needed. If you buy one somewhere else, it will not be a Verizon-authorized purchase, it certainly would not be an authorized-to-you set top box, and Verizon could not send the signal to that box to make it work.
On the horizon, though, this scenario is changing. TV manufacturers are developing TV's with slots to plug-in cable cards from whoever TV service you choose, as well as the manufacturers of the set top boxes. In fact, some of the set top boxes Verizon is delivering now have a blocked-off slot in theback for 'cards' now, so theoretically the purchase of these boxes is coming.
As to your TV in the bedroom, you need to have a set top box, especially if the digital conversion has already happened in your area (sounds like it may have if you get fuzz on your TV) [however, that line of coax to your bedroom also may not be connected to the splitter, in which case you are getting no signal to the room], if the digital conversion has not yet happened in your area, it will next month and you most definately will need a set top box. NOW, you don't have to get a QIP 2500 or bigger model. Verizon does has a smaller model (the DCT 700 digital converter) which, after the conversion, will allow that TV to get all of the same channels you get on the bigger set top boxes EXCEPT any of the premium paid stations; no VOD, no PPV, and no program guide, only the channel number.